Recently Adopted and Recently Issued Accounting Standards Details (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Change in Working Capital					$ 27,000
Adoption of new accounting standard (See Note 2)					397
Income tax expense	$ (11,234)	$ (12,000)	$ (17,487)	$ (9,834)
Stock Compensation Plan
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income tax expense	$ (500)		$ (500)
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adoption of new accounting standard (See Note 2)					$ (709)